Lamp base for elongated tubular lamps



Jan. 31, 1956 R. E. MARZ LAMP BASE FOR ELONGATED TUBULAR LAMPS Filed July 1, 1954 United States Patent LAMP BASE FOR ELONGATED TUBULAR LAMPS Ray E. Marz, Willowick, Ohio, assignor to General Electric Company, a corporation of New York Application July 1, 1954, Serial No. 440,777

2 Claims. (Cl. 339-145) The present invention relates to bases for electric lamps and similar devices, and especially for double-ended electric discharge lamps of the type having preheatable electrodes mounted at the ends of a tubular glass envelope with a pair of spaced apart current inlead wires for each of the electrodes extending from the ends of the envelope.

In the copending Lemmers application, Serial No. 380,279, filed September 15, 1953, and assigned to the assignee of the present application, two species of diskshaped bases useful for lamps of the above type are disclosed and claimed. The bases of the aforesaid copending application make possible the use of the current inlead wires at each end of the tubular lamp as the lamp terminals or contacts, thus dispensing with the usual outwardly projecting contact pins.

The bases include a disk-shaped member of electrically insulated material in which the lamp inleads are recessed for safety purposes. An inlead receiving passage extends through the disk and a recessed portion of an exposed outer face of the disk includes a slot or groove which communicates with said passage and extends transversely of the passage.

, An inlead is threaded through the passage and is bent over into and anchored in the groove. The walls of the passage are spaced apart a sufficient distance to accommodate therebetween aninlead of the lamp and an inserted electrical contact of a lamp holder and are shaped to support the accommodated inlead in position for electrical engagement with the accommodated contact.

' The groove in the body member is substantially deeper than the diameter of the accommodated inlead wire so that the inlead is recessed in the body member and the part thereof in the groove is protected from accidental contacts. The openings of the passage and the groove at the surface of the member are too small for the portions of theinlead therein to be touched accidentally in ordinary handling of the lamp. This is an important safety feature of such bases, because it eliminates the possibility of a person getting an electric shock in case something has gone wrong with the wiring of the auxilia'ry equipment for the lamp.

In one species of the base a separate passage is provided for each of the inleads. In the other species, however, a single passage is provided through the center of the insulatingdisk member and the passage is of sufficient size to accommodate both of the spaced apart inlead wires and two insulated holder contacts, one for each of the said inleads.

, In the latter species of the base a pair of aligned grooves extend in opposite directions from opposite sides of the single passa e, and the bottoms of the grooves arehpr ovidedwith narrow recesses into which the end portions of the inleads are forced to anchor the inleads in the insulating member. The inleads terminate in cavities provided in the disk at the outer ends of the grooves and additional anchoring means, such as pins passage species of the Lemmers base.

V cording to the present invention, is that the slots may ice or wedges, forced into the cavities, may be provided for the inleads.

In both species of the Lemmers base, the passage eX- tend through a raised embossed portion of the disk, and the recessed portion of the disk is in the outer exposed face of the embossment. The embossment is provided on the base for insertion in a holder for the lamp, is elongated in cross section and extends diametrically of the base across the center of the disk. In the species of the base having but a single passage for accommodating both the inleads, the cavities are located adjacent to but spaced inwardly from the ends of the elongated embossment, and the grooves extend from the cavities to the passage which is at the center of the disk.

Difficulty has been experienced in properly anchoring the inleads in the grooves and the cavities of the single The inleads must be of sufficient length to extend into the cavities and not so long as to extend into and then out of the cavities. If the inleads are too short, they cannot be properly anchored in the base; if too long, the ends thereof may be exposed on the surface of the base where they may be touched accidentally.

Heretofore, the inleads have been cut to length by hand before anchoring them in the base, but this has been unsatisfactory for mass production purposes due to the slow rate of such hand operation and the inaccuracies in the length of the cut inleads resulting in defective lamps.-

The principal object of the present invention is to provide a base of the above type in which the inleads may be properly anchored, readily and expeditiously.

' Another object of the invention is to provide a method of anchoring the inleads in such bases.

Further objects and advantages of the invention 'will appear from the following detailed description of a species thereof, from the accompanying drawing, and from the appended claims. 1

In the novel base of the present invention, the recessed portions in the outer face of the elongated embossment on the disk are extended completely across the embossment from the central passage to the ends of the embossment. The recesses thus include grooves extending from the passage toward the ends of the embossment, cavities at the ends of the grooves and slots or notches between the cavities and the ends of the-embossment.

The method of anchoring the ends of the inleads in the new base, according to the present invention, includes the steps of threading. the inleads through the. central passage of the disk; attaching the base to the lamp, and bending the inleads outwardly from each other and laterally of the base and into the recesses; severing the end portions of the inleads extending beyond the outer ends of the recesses, and crimping the remaining end portions of the inleads into the cavities to anchor the inleads in the base.

A highly desirable feature of the base structure, ac-

be utilized to properly position the inleads in thebase for cutting off the end portions thereof extending beyond the embossment by automatic means utilizing the base as part of the cutting tool.

A further feature of the invention is that the distance between the cavities and the end of the embossment, that is, the length of the slots, may be selected so that the severed ends of the inleads are recessed a proper distance within the cavities for safety purposes after the crimping step of the method has been;performed. The inleads are selected so as to be flexible for bending purposes but are of sufficient stiffness so that the crimping of the: ends thereof in the cavities in the disk is effectively-for firmly anchoring the inleads in the base.

, In the drawing accompanying and forming part of this specification, an embodiment of the invention is shown in which:

Fig. l is a side elevational view of a double-ended electric discharge lamp provided with bases embodying the invention;

Fig. 2 is a sectional view of one end of the based lam shown in Fig. 1;

Fig. 3 is a front plan view of the base shown in Fig. 2 with the wire inleads omitted to show the recessed parts of the base, and

Fig. 4 is a plan view of the back of the base shown in Figs. 2 and 3 with the inleads omitted.

Referring to Fig. 1 of the drawing, in which like numbers denote like parts in all figures, the double-ended electric discharge lamp comprises a tubular sealed glass envelope 1 provided with bases 2 and 3 attached to its ends. The bases 2 and 3'are of identical structure and the internal parts of only the base 3 have been shown in Figs. 2, 3 and 4 for conciseness in description.

The base 3 comprises an annular metal shell 4, which is suitably made of sheet aluminum, and a disk 5 of electrically insulating material, such as an organic plastic.

The disk 5 may be made of commercial plastic molding compounds, such as those comprising phenol-furfural resins or phenolic resins. The inner rim of the shell 4 is embedded in the periphery of the insulating disk 5 to mechanically join these base members, as shown in Figs. 2 to 4. The base 3 is secured to the end of the glass envelope 1 by a body of basing cement 6.

The disk 5 has a raised elongated embossment 7 extending across its center and projecting outwardly from the base for insertion in holders (not shown) for the lamp. A hexagonal passage 8, slightly flattened so as to be elongated in cross section, is provided in the embossed portion 7 of t .e disk 5. The metal wire current inleads 9 and 10 connected to the ends of the electrode 11 and extending through the press 12 of the stem 13 of the glass envelope 1 extend through the passage 8 in the disk 5 of the base 3 and constitute electrical terminals for the lamp.

The outer face 18 of the embossment 7 is recessed in part and includes two outwardly opening cavities 14 and 15 spaced from the central passage 8. The cavities 14 and 15 are connected to the passage 8 by the short grooves 16 and 17 (Fig. 3). Also, the outer face 18 of the embossment 7 is slotted between the cavities 14 and 15 and its ends, as shown at 19 and 20 in Figs. 2 and 3, so that the inlead wires 9 and 10 may be laid into the grooves 16 and '17, across the cavities 14 and 15' and extend through the slots 19 and 20 and beyond the rounded ends 21 and 22 of the embossment 7, as shown in broken lines in Fig. 2. This arrangement of these parts of the recessed portion of the base facilitates the anchoring of the inleads 9 and 10 in the disk 5 of the base 3 by the method described below.

After the inleads 9 and 10 have been so positioned on the disk 5, the portions thereof extending beyond the rounded ends 21 and 22 of the embossment 7 are cut off flush with the said ends of the embossment and the parts of the inleads overlying the cavities 14 and 15 are crimped into the cavities to anchor the inleads 9 and 10 in the base 3 ,as shown in full lines in Fig. 2.

The depth of the grooves 16 and 17 and the cavaties 14 and 15 is made greater than the diameter of the inlead wires 9 and 10 accommodated therein, and the width of the passage 8 and that of grooves 16 and 17 and slots 19 and 20 is made narrow so that the inleads are recessed within the insulating disk and accidental contacts with the said inleads cannot occurin handling the lamp incident to its mounting ordismounting in electrical apparatus including holders forthe lamp. This is an important safety'feature of the base structure.

In mounting the base 3 on the ends of the lamp enve lope 1, the basing cement 6 is applied to the inner surfaceof the metal shell 4.- The inleads 9 and 10 are threaded 4 through a guide slot 24 defined by a molded integral part 25 (Figs. 2 and 4) of the disk 5 located at the inner end of the passage 8 to direct the inleads 9 and 10 in proper spaced positions in said passage when moved laterally of the passage, as described and claimed in the co-pending Grovemiller application, Serial No. 440,780, of even date herewith, and assigned to the assignee of the present application.

After the inleads have been so threaded through the slot and the passage, the base 3 is pressed onto the end of the envelope 1 to compress the basing cement '6 between the shell 4 and the envelope 1. The cement is allowed to harden to secure the base 3 to the envelope 1. Thereafter the inleads 9 and 10 are spread apart and the outer end portions thereof are bent over into the grooves 16 and 17 and the slots 19 and 20 in the face of the embossment 7, as shown in broken lines in Fig. 2.

The lateral movement of the portions of the inleads 9 and 10 in the passage 8 is guided by the edges of the guide slot 24, as aforesaid, so that the inleads 9 and 10 are moved into the ends of the guide slot. The portions of the inleads 9 and 10 in the passage 8 are thus guided into spaced parallel positions against the vertices of the convergent end walls of the hexagonal passage 8 for engagement with the holder contacts received in the passage 8 when mounting the based lamp in a lamp holder.

After the outer end portions of the inleads 9 and 10 have been bent over so as to lie in the grooves 16 and 17 and the slots 19 and 20, as shown in Fig. 2, the parts thereof extending beyond the outer ends of the slots are severed flush with the rounded surface of the ends 21 and 22 of the embossment. The parts of the inleads overlying the cavities 14 and 15 are then crimped into the cavities to anchor the inleads securely in the disk 5, as shown in full lines in Fig. 2. It will be noted that the severed end of each inlead terminates in the cavity and slightly below the bottom of the slot so as to assure protection of the inleads against accidental contacts in handling of the lamp.

The lamp shown in side elevation in Fig. 1 of the drawing may be about 8 feet in length and about 1 /2 inches in diameter. The electrodes 11 sealed into the ends of the envelope 1 each comprises a tungsten filament coated with electron-emissive material, such as alkaline-earth compounds, and each is of the type requiring preheating to an electron emitting temperature before starting of an electric discharge between the said electrodes at opposite ends of the lamp envelope. The envelope 1 contains a starting gas, such as argon, at a few millimeters pressure and a small measured quantity 26 of mercury, the vapor of which is at a pressure of about 10 microns during operation of the lamp. A coating 27 of fluorescent material is provided on the inner surface of the envelope 1 and this material is excited to luminescence by the intense emission of 2537 A. radiation of the low-pressure mercury vapor discharge during oper ation of. the lamp. Such lamps are commercially available and a species thereof is known in the trade as the rapid start fluorescent lamp.

What. I claim as new and desire to secure by Letters Patent of the United States is:

1. A base for attachment to an end of an electric lamp envelope having a pair of spaced wire inleads extending from the said envelope end, said base compris ing an outwardly projecting electrically insulating body member provided with a passage for receiving both said spaced inleads and electrical supply contacts of aholder for said lamp, the outer face of said member having inlead receiving recessed portions greater in depth than the inleads for which the base is designed and communicating with said passage for accommodating the end portions of inleads threaded through said passage, said recesses extendin completely across the said outer face of said member from said passage whereby the end por-.

tions of inleads threaded through said passage and bent over into said recesses extend laterally beyond the said outer face of said member to facilitate cutting said inleads to proper length in the manufacture of a based lamp, each of said recesses having a cavity opening thereinto, extending into said member and spaced from said passage, the walls of said cavity being spaced apart a sufiicient distance to accommodate therebetween and anchor in said base a crimped end of a cut inlead, the wall of said passage and the portions of said spaced recesses between said cavities and said passage being shaped to support the portions of the inleads accommodated therein in spaced positions for engagement with insulated electrical supply contacts of a holder for said lamp.

2. A base for attachment to an end of an electric lamp envelope having a pair of spaced wire inleads extending from the said envelope end, said base comprising a disk-shaped electrically insulating body member having an outwardly projecting raised elongated embossment for insertion in a lamp holder, an inlead receiving passage through the embossed portion thereof and recesses in the face of said embossment extending in opposite directions along said embossment from said passage, each of said recesses being greater in depth than the diameter of the inleads for which the base is designed and including a cavity opening into the recess and positioned between the said passage and an end of said elongated embossment, each of said recesses including also a groove connecting said cavity with said passage and a slot extending from said cavity to the respective end of said embossment whereby the end portions of inleads threaded through said passage and bent over into said recesses extend beyond the ends of said embossment to facilitate cutting said inleads to proper length in the manufacture of a based lamp, the walls of each of said cavities being spaced apart a proper distance to accommodate therebetween and anchor in said base a crimped end of a cut inlead, the walls of said passage and said grooves being shaped to support the portions of the in leads accommodated therein in spaced positions in said base for engagement with insulated electrical supply contacts of a holder for said lamp.

References Cited in the file of this patent UNITED STATES PATENTS 693,222 Boehm Feb. 11, 1902 2,033,748 Wallace Mar. 10, 1936 2,039,957 Hall May 5, 1936 

